Biomarkers in acute coronary syndromes and their role in diabetic patients

Berberine activates peroxisome proliferator-activated receptor gamma to increase atherosclerotic plaque stability in Apoe-/- mice with hyperhomocysteinemia

AIMS/INTRODUCTION

An elevated level of plasma homocysteine has long been suspected as a metabolic risk factor for the development of atherosclerotic vascular diseases in diabetes. Berberine (BBR) has several preventive effects on cardiovascular diseases. The effects of BBR on atherosclerotic plaque stability increased by homocysteine thiolactone (HTL) remain unknown.

MATERIALS AND METHODS

The model of atherosclerotic vulnerable plaque was induced by placing a collar around the carotid artery in Apoe-/- mice. Endothelium-dependent relaxation was assayed by organ chamber.

RESULTS

Homocysteine thiolactone (50 mg/kg/day, 8 weeks) reduced the atherosclerotic plaque stability in the carotid artery of Apoe-/- mice, which was reversed by BBR administration (1.0 g/kg/day). In vivo and ex vivo experiments showed that HTL dramatically reduced acetylcholine-induced endothelium-dependent relaxation and superoxide dismutase activity, and increased malondialdehyde content, which were inhibited by BBR. Importantly, all effects induced by BBR were abolished by GW9662, an antagonist of peroxisome proliferator-activated receptor-γ. Incubation of cultured endothelial cells with HTL significantly reduced cell viabilities and enhanced production of reactive oxygen species. Pretreatment of cells with BBR dose-dependently reversed HTL-induced detrimental effects, which were GW9662-reversible.

CONCLUSIONS

Berberine increases atherosclerotic plaque stability in hyperhomocysteinemia mice, which is related to the activation of peroxisome proliferator-activated receptor-γ and subsequent suppression of oxidative stress in endothelial cells.

Lentivirus-mediated RNA interference of chymase increases the plaque stability in atherosclerosis in vivo

Chymase activity was proved to be closely related with plaque vulnerability in a hamster model of atherosclerosis with chymase inhibitors. Considering that chymase inhibitors are nonspecific, here we further investigated the role of chymase in atherosclerosis in vivo through injection of lentivirus containing chymase shRNA or chymase cDNA. Our results revealed that silencing of the chymase gene by shRNA remarkably enhanced atherosclerosis plaque stability without alterations in body weight or serum lipid levels. Lentiviral expression of a gain-of-function chymase gene promoted the formation of vulnerable plaque in hamsters. Mechanistically, chymase functions as an activator of MMP9 in atherosclerotic lesions that induces plaque instability.